When an author talks about a deadline, it's usually not meant to be taken literally. But "The Investment Answer" came about as a response to co-author Gordon Murray's diagnosis with a brain tumor.

Six months ago, Murray was diagnosed with a a glioblastoma -- the same type of tumor that finally took Ted Kennedy's life. Murray had already been through this before, and knew the toll that treatment would take.

"You go through an initial period of sadness, but then you realize, 'Okay, I can't do anything about it, so let's just make the most of what we have,'" Murray said. "I could have a great, quality six months, or I could take the risk with the chemo, the radiation, and all these other drugs they throw in you, but it might actually make things worse."

Murray decided to forgo treatment, and time became a precious commodity, not to be wasted. As he started calling relatives and friends to tell them the news, one friend had an idea as to how Murray should spend his final months.

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Murray told his friend and financial planner Dan Goldie about his diagnosis and, "literally, without missing a beat, he said, 'Do you want to do that book you've always wanted to do?'" Murray recalled.

The book is a how-to guide to investing for retirement, a subject Murray knows a thing or two about. For 25 years, he was one of those "Masters of the Universe" on Wall Street, managing huge institutional investments at Goldman Sachs, Lehman Brothers and Credit Suisse First Boston.

One of the main goals of the book is to demystify investing, to take it back from the whiz kids on Wall Street. The investment book is his offering of atonement, if not for his sins, then perhaps for the sins of the Street.

"I wanted to feel good about what I had done, because you go back to the mid-to-late 70's, Wall Street performed a function that was actually good for Main Street... match investors who need to raise money with investors who have money," Murray said.

That began to change, he said, partly because some bankers put aside ethics in favor of profits and ignored the tenet that the client comes first.

Investment Banker Dedicates Final Months to Helping Average Investors

Through the book, Murray wanted to restack the odds in favor of the ordinary investor.

"If you're an long-term investor, there are a lot of things you can do," Murray said. "Speculating is trying to pick stocks and find mispriced securities and time the markets."

The book lays out five basic questions that every investor must answer.

Should you do it yourself, or hire a professional?

"Investing is complex... You need help," Murray said.

How do you allocate your assets?

"Risk and return are related. Don't just look at returns," he explained.

How do you diversity effectively?

"A lot of people think, 'Yes, I know diversification. I've sold my one tech stock and bought 10 other tech stocks,'" Murray said, noting that similar assets are subject to similar risks. "The reality is some asset classes zig and others zag... so when you layer them together, you can lower that risk."

Should you try to beat the market or rise with it?

"There's a global capital market rate of return which is there for the taking. That's what we call investing as opposed to speculating," he said.

And finally, how often do you need to make adjustments?

"One of the most surprising aspects of the book is that we've had billionaires, hedge fund managers, sophisticated investors say, 'You know, I didn't know this or I didn't know that,'" Murray said, explaining that people will have to read the book to understand it all.

Author Gordon Murray: 'You Focus on What You Can Control'

What's so extraordinary is that Murray felt such a burning desire to share this financial knowledge when he knew he had such little time left.

"I'm not religious, but I just think it's like investing -- you focus on what you can control," Murray said. "And I can't control how fast this tumor is growing... All you've got is each minute."

We met Gordon the week before Christmas, and a month later, he's gone. He died at home last Saturday, having enjoyed every minute with family and friends.

But Murray met his deadline. His book, "The Investment Answer," will be published next week.